'use strict';

var http = require('http');
var https = require('https');
var url = require('url');

function debug() {
  if (module.exports.debug) {
    console.log.apply(console, arguments);
  }
}

function mergeOrDelete(defaults, updates) {
  Object.keys(defaults).forEach(function (key) {
    if (!(key in updates)) {
      updates[key] = defaults[key];
      return;
    }

    // neither accept the prior default nor define an explicit value
    // CRDT probs...
    if ('undefined' === typeof updates[key]) {
      delete updates[key];
    } else if ('object' === typeof defaults[key] && 'object' === typeof updates[key]) {
      updates[key] = mergeOrDelete(defaults[key], updates[key]);
    }
  });

  return updates;
}

// retrieves an existing header, case-sensitive
function getHeaderName(reqOpts, header) {
  var headerNames = {};
  Object.keys(reqOpts.headers).forEach(function (casedName) {
    headerNames[casedName.toLowerCase()] = casedName;
  });
  // returns the key, which in erroneous cases could be an empty string
  return headerNames[header.toLowerCase()];
}
// returns whether or not a header exists, case-insensitive
function hasHeader(reqOpts, header) {
  return 'undefined' !== typeof getHeaderName(reqOpts, header);
}

function toJSONifier(keys) {

  return function () {
    var obj = {};
    var me = this;

    keys.forEach(function (key) {
      if (me[key] && 'function' === typeof me[key].toJSON) {
        obj[key] = me[key].toJSON();
      } else {
        obj[key] = me[key];
      }
    });

    return obj;
  };
}

function setDefaults(defs) {
  defs = defs || {};

  function urequestHelper(opts, cb) {
    debug("\n[urequest] processed options:");
    debug(opts);

    function onResponse(resp) {
      var followRedirect;

      Object.keys(defs).forEach(function (key) {
        if (key in opts && 'undefined' !== typeof opts[key]) {
          return;
        }
        opts[key] = defs[key];
      });
      followRedirect = opts.followRedirect;

      resp.toJSON = toJSONifier([ 'statusCode', 'body', 'headers', 'request' ]);

      resp.request = req;
      resp.request.uri = url.parse(opts.url);
      //resp.request.method = opts.method;
      resp.request.headers = finalOpts.headers;
      resp.request.toJSON = toJSONifier([ 'uri', 'method', 'headers' ]);

      if (followRedirect && resp.headers.location && -1 !== [ 301, 302, 307, 308 ].indexOf(resp.statusCode)) {
        debug('Following redirect: ' + resp.headers.location);
        if ('GET' !== opts.method && !opts.followAllRedirects) {
          followRedirect = false;
        }
        if (opts._redirectCount >= opts.maxRedirects) {
          followRedirect = false;
        }
        if ('function' === opts.followRedirect) {
          if (!opts.followRedirect(resp)) {
            followRedirect = false;
          }
        }
        if (followRedirect) {
          if (!opts.followOriginalHttpMethod) {
            opts.method = 'GET';
            opts.body = null;
            delete opts.headers[getHeaderName(opts, 'Content-Length')];
            delete opts.headers[getHeaderName(opts, 'Transfer-Encoding')];
          }
          if (opts.removeRefererHeader && opts.headers) {
            delete opts.headers.referer;
          }
          // TODO needs baseUrl, maybe test for host / socketPath?
          opts.url = resp.headers.location;
          opts.uri = url.parse(opts.url);
          return urequestHelper(opts, cb);
        }
      }
      if (null === opts.encoding) {
        resp._body = [];
      } else {
        resp.body = '';
      }
      resp._bodyLength = 0;
      resp.on('data', function (chunk) {
        if ('string' === typeof resp.body) {
          resp.body += chunk.toString(opts.encoding);
        } else {
          resp._body.push(chunk);
          resp._bodyLength += chunk.length;
        }
      });
      resp.on('end', function () {
        if ('string' !== typeof resp.body) {
          if (1 === resp._body.length) {
            resp.body = resp._body[0];
          } else {
            resp.body = Buffer.concat(resp._body, resp._bodyLength);
          }
          resp._body = null;
        }
        if (opts.json && 'string' === typeof resp.body) {
          // TODO I would parse based on Content-Type
          // but request.js doesn't do that.
          try {
            resp.body = JSON.parse(resp.body);
          } catch(e) {
            // ignore
          }
        }

        debug("\n[urequest] resp.toJSON():");
        debug(resp.toJSON());
        cb(null, resp, resp.body);
      });
    }

    var req;
    var finalOpts = {};
    var _body;
    var MyFormData;
    var form;
    var formHeaders;
    var requester;

    if (opts.body) {
      if (true === opts.json) {
        _body = JSON.stringify(opts.body);
      } else {
        _body = opts.body;
      }
    } else if (opts.json && true !== opts.json) {
      _body = JSON.stringify(opts.json);
    } else if (opts.form) {
      _body = Object.keys(opts.form).filter(function (key) {
        if ('undefined' !== typeof opts.form[key]) {
          return true;
        }
      }).map(function (key) {
        return encodeURIComponent(key) + '=' + encodeURIComponent(String(opts.form[key]));
      }).join('&');
      opts.headers['Content-Type'] = 'application/x-www-form-urlencoded';
    }
    if ('string' === typeof _body) {
      _body = Buffer.from(_body);
    }

    Object.keys(opts.uri).forEach(function (key) {
      finalOpts[key] = opts.uri[key];
    });
    finalOpts.method = opts.method;
    finalOpts.headers = JSON.parse(JSON.stringify(opts.headers));
    if (_body) {
      // Most APIs expect (or require) Content-Length except in the case of multipart uploads
      // Transfer-Encoding: Chunked (the default) is generally only well-supported downstream
      finalOpts.headers['Content-Length'] = _body.byteLength || _body.length;
    }
    if (opts.auth) {
      // if opts.uri specifies auth it will be parsed by url.parse and passed directly to the http module
      if ('string' !== typeof opts.auth) {
        opts.auth = (opts.auth.user||opts.auth.username||'') + ':' + (opts.auth.pass||opts.auth.password||'');
      }
      if ('string' === typeof opts.auth) {
        finalOpts.auth = opts.auth;
      }
      if (false === opts.sendImmediately) {
        console.warn("[Warn] setting `sendImmediately: false` is not yet supported. Please open an issue if this is an important feature that you need.");
      }
      if (opts.bearer) {
        // having a shortcut for base64 encoding makes sense, but this? Eh, whatevs...
        finalOpts.header.Authorization = 'Bearer: ' + opts.bearer;
      }
    }
    if (opts.formData) {
      try {
        MyFormData = opts.FormData || require('form-data');
        // potential options https://github.com/felixge/node-combined-stream/blob/master/lib/combined_stream.js#L7-L15
      } catch(e) {
        console.error("urequest does not include extra dependencies by default");
        console.error("if you need to use 'form-data' you may install it, like so:");
        console.error("  npm install --save form-data");
        cb(e);
        return;
      }
      try {
        form = new MyFormData();
        Object.keys(opts.formData).forEach(function (key) {
          function add(key, data, opts) {
            if (data.value) { opts = data.options; data = data.value; }
            form.append(key, data, opts);
          }
          if (Array.isArray(opts.formData[key])) {
            opts.formData[key].forEach(function (data) {
              add(key, data);
            });
          } else {
            add(key, opts.formData[key]);
          }
        });
      } catch(e) {
        cb(e);
        return;
      }
      formHeaders = form.getHeaders();
      Object.keys(formHeaders).forEach(function (header) {
        finalOpts.headers[header] = formHeaders[header];
      });
    }

    // TODO support unix sockets
    if ('https:' === finalOpts.protocol) {
      // https://nodejs.org/api/https.html#https_https_request_options_callback
      debug("\n[urequest] https.request(opts):");
      debug(finalOpts);
      requester = https;
    } else if ('http:' === finalOpts.protocol) {
      // https://nodejs.org/api/http.html#http_http_request_options_callback
      debug("\n[urequest] http.request(opts):");
      debug(finalOpts);
      requester = http;
    } else {
      cb(new Error("unknown protocol: '" + opts.uri.protocol + "'"));
      return;
    }

    if (form) {
      debug("\n[urequest] '" + finalOpts.method + "' (request) form");
      debug(formHeaders);
      // generally uploads don't use Chunked Encoding (some systems have issues with it)
      // and I don't want to do the work to calculate the content-lengths. This seems to work.
      req = form.submit(finalOpts, function (err, resp) {
        if (err) { cb(err); return; }
        onResponse(resp);
        resp.resume();
      });
      //req = requester.request(finalOpts, onResponse);
      //req.on('error', cb);
      //form.pipe(req);
      return;
    }

    req = requester.request(finalOpts, onResponse);
    req.on('error', cb);

    if (_body) {
      debug("\n[urequest] '" + finalOpts.method + "' (request) body");
      debug(_body);
      // used for chunked encoding
      //req.write(_body);
      // used for known content-length
      req.end(_body);
    } else {
      req.end();
    }
  }

  function parseUrl(str) {
    var obj = url.parse(str);
    var paths;
    if ('unix' !== (obj.hostname||obj.host||'').toLowerCase()) {
      return obj;
    }

    obj.href = null;
    obj.hostname = obj.host = null;

    paths = (obj.pathname||obj.path||'').split(':');

    obj.socketPath = paths.shift();
    obj.pathname = obj.path = paths.join(':');

    return obj;
  }

  function urequest(opts, cb) {
    debug("\n[urequest] received options:");
    debug(opts);
    var reqOpts = {};
    // request.js behavior:
    // encoding: null + json ? unknown
    // json => attempt to parse, fail silently
    // encoding => buffer.toString(encoding)
    // null === encoding => Buffer.concat(buffers)
    if ('string' === typeof opts) {
      opts = { url: opts };
    }

    module.exports._keys.forEach(function (key) {
      if (key in opts && 'undefined' !== typeof opts[key]) {
        reqOpts[key] = opts[key];
      } else if (key in defs) {
        reqOpts[key] = defs[key];
      }
    });

    // TODO url.resolve(defs.baseUrl, opts.url);
    if ('string' === typeof opts.url || 'string' === typeof opts.uri) {
      if ('string' === typeof opts.url) {
        reqOpts.url = opts.url;
        reqOpts.uri = parseUrl(opts.url);
      } else if ('string' === typeof opts.uri) {
        reqOpts.url = opts.uri;
        reqOpts.uri = parseUrl(opts.uri);
      }
    } else {
      if ('object' === typeof opts.uri) {
        reqOpts.url = url.format(opts.uri);
        reqOpts.uri = opts.uri;
        //reqOpts.uri = url.parse(reqOpts.uri);
      } else if ('object' === typeof opts.url) {
        reqOpts.url = url.format(opts.url);
        reqOpts.uri = opts.url;
        //reqOpts.uri = url.parse(reqOpts.url);
      }
    }

    if (opts.body || 'string' === typeof opts.json || opts.form || opts.formData) {
      // TODO this is probably a deviation from request's API
      // need to check and probably eliminate it
      reqOpts.method = (reqOpts.method || 'POST').toUpperCase();
    } else {
      reqOpts.method = (reqOpts.method || 'GET').toUpperCase();
    }
    if (!reqOpts.headers) {
      reqOpts.headers = {};
    }

    // crazy case for easier testing
    if (!hasHeader(reqOpts, 'CoNTeNT-TyPe')) {
      if ((true === reqOpts.json && reqOpts.body)
        || (true !== reqOpts.json && reqOpts.json)) {
        reqOpts.headers['Content-Type'] = 'application/json';
      }
    }

    return urequestHelper(reqOpts, cb);
  }

  urequest.defaults = function (_defs) {
    _defs = mergeOrDelete(defs, _defs);
    return setDefaults(_defs);
  };
  [ 'get', 'put', 'post', 'patch', 'delete', 'head', 'options' ].forEach(function (method) {
    urequest[method] = function (obj) {
      if ('string' === typeof obj) {
        obj = { url: obj };
      }
      obj.method = method.toUpperCase();
      urequest(obj);
    };
  });
  urequest.del = urequest.delete;

  return urequest;
}

var _defaults = {
  sendImmediately: true
, method: 'GET'
, headers: {}
, useQuerystring: false
, followRedirect: true
, followAllRedirects: false
, followOriginalHttpMethod: false
, maxRedirects: 10
, removeRefererHeader: false
//, encoding: undefined
, gzip: false
//, body: undefined
//, json: undefined
};
module.exports = setDefaults(_defaults);

module.exports._keys = Object.keys(_defaults).concat([
  'encoding'
, 'body'
, 'json'
, 'form'
, 'auth'
, 'formData'
, 'FormData'
]);
module.exports.debug = (-1 !== (process.env.NODE_DEBUG||'').split(/\s+/g).indexOf('urequest'));

debug("DEBUG ON for urequest");
